The most common and most likely answer to this crossword clue is the 4 plus 3 letter word LUMP SUM
I've seen this crossword clue in The Guardian
L
U
M
P
S
U
M
More clues leading to the result LUMP SUM
- Kind of fish on top of whole chunk of bread?
- Deposit, say, posh pharmacist in Hebridean stack
- Politicians invested in large universities with millions in one-off payment
- A whole chunk of bread?
- Spooner’s giving you a little fruit wedge?
- Payment for records with hesitation during – and after
- Sugar, perhaps, needing part, say, for complete payment
- Payment is a problem after swelling
- Tolerate problem to get complete amount
- Consequences of assault, perhaps, with some hesitation, producing single pay-out?
Buddy explains!

The straight part
We know that "complete payment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case complete payment = lump sum.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.